1. Field of the Invention
This invention relates to a wake-up device for electronic input devices having a power-saving sleep mode, and more particularly to a sound-activated wake-up device that causes an electronic input device to xe2x80x9cwake-upxe2x80x9d or terminate a power-saving sleep mode upon detection of a sound, in order to enable full-power operation of the device.
2. Description of Related Art
As electronic technology has progressed, electronic devices have become lighter, thinner, shorter, and smaller. In addition, there has been a trend toward devices having low power consumption. In the case of information processing facilities, such as computers, personal digital assistants (PDAs), and portable communication devices, which are becoming more and more popular, low power consumption has become a key selling point, particularly with respect to battery-powered input, output, and/or communications devices such as wireless communications handsets, electronic mouses, keyboards, trackballs, game controllers, PC cameras.
To achieve acceptably low power consumption, it has become necessary to include a power-saving or xe2x80x9csleepxe2x80x9d mode in such devices. The sleep mode reduces power consumption to the minimum necessary to maintain essential functions when the device is not in use, by causing high energy consumption components such as central processing units (CPUs) or micro control units (MCUs) to stop running after a predetermined period of inactivity, thus extending the life of any batteries within the device. This is particularly important in wireless devices, for which batteries are likely to be the sole power source.
While most conventional power-saving or sleep-mode initiating circuits are essentially the same, wake-up devices vary widely. One type of conventional wake-up device, for example, periodically outputs a wake-up signal based on predetermined time intervals to check whether a user is operating the device. This type of wake-up device has the greatest power consumption, even when the checking process is relatively short, because the periodic supply of full power to the device occurs whether or not use of the device is desired. Another conventional type of wake-up device, on the other hand, detects a button clicking or movement of the device to initiate wake-up. Such a device, an example of which is disclosed in U.S. Pat. No. 5,854,621, while convenient in many ways, can cause problems in devices used as computer inputs since the button clicking will be taken as a command following wake-up. This which might result in undesirable occurrences such as the deletion of a file before the button-clicking user realizes that wake-up has already been completed and is able to appreciate the consequences of continued button pushing.
Other conventional wake-up devices detect the movement of an input device or other physical actions. For example, the device disclosed in Japanese Patent Publication No. JP11212721 generates a wake-up signal upon touching of the device, while Japanese Patent Publications JP11224158 and JP11242560 disclose devices that generate wake-up signals upon detection of vibrations. While these devices optimize power consumption for input devices connected to a computer, however, the power savings obtained are still not optimal since the devices will wake-up whether or not connected to a computer, and further are responsive to unintended as well as intended touches or vibrations.
Finally, yet another conventional wake-up device design proposed by Microsoft Corporation uses a detector to sense changes in an induced magnetic field between the user and the input device. This design has the disadvantages of requiring a periodic, albeit brief, wake-up to check the detector, and involves use of a relatively expensive magnetic field sensor.
In summary, despite the numerous different wake-up device designs that have previously been proposed, a wake-up device is still needed that initiates wake-up only in the presence of a user, without being subject to other environmental influences, and only under conditions in which full-power can be utilized, and yet that is small, lightweight, reliable, and relatively inexpensive.
It is accordingly an objective of the present invention to provide a wake-up device having a simple structure, that is low in cost, and that is easily carried, and that reliably initiates wake-up of an electronic device, such as an input device, only when necessary, i.e., in the presence of a user under conditions in which full-power to the electronic device can be utilized.
This objective is achieved, in accordance with the principles of a preferred embodiment of the invention, by providing a sound-activated wake-up device for use in a wireless input device having an MCU with a sleep mode function. By utilizing sounds as the activation source, and by choosing sounds having unique signatures or characteristics such as a particular range of frequencies or a low level, the wake-up device of the invention is capable of making finer distinctions as to the actual source than is possible with a vibration or field detector, thereby greatly improving the reliability by which the presence of a user can be detected and distinguished from background or ambient effects.
The sound-activated wake-up device of the preferred embodiment includes a sound detecting unit capable of detecting low level sounds such as the sound caused by friction between the input device and an operating platform, or a user touching the input device. A signal amplifying/comparing unit connected to the sound detecting unit analyzes received sounds and outputs a wake-up signal to the MCU if an appropriate sound is detected.
In order to precisely detect the selected sounds, the body of the input device is preferably made of a noise-proof material, and/or may include a noise or bandpass filter for eliminating background noise. The input device can be, but is not limited to, such electronic input devices as wireless rouses, wireless keyboards, wireless game controllers, PC cameras, and so forth.
Further objectives and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawings.